Silk fibroin has excellent film-forming capabilities and is also compatible for use in the human body. Silk fibroin films, without further manipulation or treatment, are soluble in water because of dominating random coil protein structures. The structural features of the protein can be transformed from random coil to β-sheet structure by several treatments, including mechanical stretching, immersion in polar organic solvents, or curing in water vapor. This structural transition results in aqueous insolubility, thus providing options for the use of the material in a range of biomedical and other applications. Some pure silk fibroin films tend, over time, to become stiff and brittle in the dry state, however, exhibiting impressive tensile strength but low ductility. There remains a need to modify the physical and mechanical properties of silk fibroin films to improve mechanical properties and provide for more flexible silk fibroin-based systems for biomedical and other applications.